Guardian Series Automatic Battery Chargers
Guardian Series Automatic Battery Chargers


  • Heavy duty float charging: 10A or 20A @ 12 VDC or 24 VDC
  • Lead acid or NiCd batteries
  • Auto boost operation
  • Temperature compensation
  • NFPA 110 alarm outputs: charge fail, under volts & over volts
  • Short circuit and reverse polarity protection



The Guardian is a highly efficient, high performance battery charger. The output is configured for accurate fast charging, optimum battery life and reliability. High impedance transformer technology gives a low ripple output (<1%) suitable for charging either sealed or vented batteries, e.g. Nickel Cadmium (NiCd), sealed lead acid (VRLA), vented and Plante' cells. The Guardian range can be used in a wide range of industrial charging applications, including standby engines, pumps and generators.


Each charger consists of a transformer, rectifier and control circuit, in an open frame assembly for easy panel mounting. The control circuit ensures that the charger maintains the battery voltage at the pre-calibrated float level, while supplying any additional load current up to the specified maximum.



Auto boost operation provides a temporary increase in output voltage, equalising the battery charge between cells and maximizing battery life and capacity. Auto boost is triggered automatically when the battery falls below a preset voltage. Once the batteries have reached the boost voltage level, Guardian reverts to its normal float charge mode, preventing battery over-charge and gassing.


Auto boost can also be initiated manually (regardless of battery voltage) by linking two ‘boost’ terminals, e.g. via a panel switch or push-button. 



The optimum charge voltage for lead acid and NiCd batteries varies with ambient temperature. All Guardian chargers can be configured (using circuit board links) with automatic output temperature compensation, either by on- board sensor, or by RTC option remote sensor with 3m lead.


When temperature compensation is enabled, output voltage decreases as ambient temperature increases at a rate of 3mV/°C/cell (see calibration table overleaf). 



The Guardian provides 3 x NFPA110 compliant alarm relay outputs: battery high volts and battery low volts (both with 120 sec delay) and charge fail. 



Mounting is via slots in the transformer frame. Spring clamp terminals provide secure electrical connection to panel wiring. AC supply input and DC charge output are protected with circuit-board mounted fusing.


Please see installation and operation instructions for full details. 

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